Authors : Kapil Kumar Singh and Pawan Agarwal

Synopsis
Internet is the backbone of the Information Technology (IT) in the present world. Internet comprises of a large number of heterogenous networks combined together to form a large network. These networks have got limited capacity in terms of bandwidth etc. The number of users is increasing at atronomical rate thereby overloading the network and worsening the problem of congestion.

In this paper, we have explained how pricing can be an effective means not only to recover costs, but to allow the user to select among different options for service in a controlled manner and hence relieving congestion. For example, users might like the option of purchasing either more or less capacity on the network during periods of congestion. Traditionally, the Internet technical community has not concerned itself with pricing. Technologists preferred to implement technical solutions to allocate bandwidth. The Internet has implemented one service class, and used a technical means rather than a pricing means to allocate resources when the network is fully loaded and congestion occurs.

But while pricing can be changed quickly, the deployment of technical mechanisms inside the network (involving changes to the packet switches, or routers) can take lots of effort and hence are difficult to accomplish. In the paper, we have tried to analyse various methods, based on pricing techniques, to relieve congestion. We have anlyzed the various pros and cons of these schemes and find out what problems they face for a practical and reasonable implementation.

First scheme we have analysed is the Smart Market Scheme based on the use of a 'bid' field in the IP header of the packet. Packets with bid higher than the equilibrium price is sent through and others are dropped. Second is Paris Metro Pricing (PMP) Scheme which proposes to divide network into logical divisions with different usage price and as a result, network with higher price will be less used hence less congested. Next is the Zone Payment Scheme based on division of the network into zones according to users' choice and when sender and receiver have a common zone, transmission gets the highest priority. In Priority Pricing Scheme, we have various service classes with different priorities and transmission in a congested network is based on priority of these classes. Expected Capacity Service Scheme provides the user, according to his choice, a predefined network capacity and user can transmit pakets without feeling the effect of congestion if the transmission rate is below the capacity, otherwise the packet may be dropped. The Edge Pricing Scheme suggests that pricing must be done based on expected congestion levels along the expected path appropriate for the packet's source. The Billing Gateway (BGW) Scheme controls users' access to a billed link by allowing or diallowing TCP connection using a gateway and by metering users' TCP traffic once a connection has been established.

At the end, we have accumulated the plus points of the above schemes and concluded by suggesting our own scheme.